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/* Thread-local storage handling in the ELF dynamic linker. x86_64 version.
Copyright (C) 2004-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#ifndef SECTION
# define SECTION(p) p
#endif
#undef REGISTER_SAVE_AREA
#undef LOCAL_STORAGE_AREA
#undef BASE
#include "dl-trampoline-state.h"
.section SECTION(.text),"ax",@progbits
.hidden _dl_tlsdesc_dynamic
.global _dl_tlsdesc_dynamic
.type _dl_tlsdesc_dynamic,@function
/* %rax points to the TLS descriptor, such that 0(%rax) points to
_dl_tlsdesc_dynamic itself, and 8(%rax) points to a struct
tlsdesc_dynamic_arg object. It must return in %rax the offset
between the thread pointer and the object denoted by the
argument, without clobbering any registers.
The assembly code that follows is a rendition of the following
C code, hand-optimized a little bit.
ptrdiff_t
_dl_tlsdesc_dynamic (register struct tlsdesc *tdp asm ("%rax"))
{
struct tlsdesc_dynamic_arg *td = tdp->arg;
dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET);
if (__builtin_expect (td->gen_count <= dtv[0].counter
&& (dtv[td->tlsinfo.ti_module].pointer.val
!= TLS_DTV_UNALLOCATED),
1))
return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset
- __thread_pointer;
return __tls_get_addr_internal (&td->tlsinfo) - __thread_pointer;
}
*/
cfi_startproc
.align 16
_dl_tlsdesc_dynamic:
_CET_ENDBR
/* Preserve call-clobbered registers that we modify.
We need two scratch regs anyway. */
movq %rsi, -16(%rsp)
mov %fs:DTV_OFFSET, %RSI_LP
movq %rdi, -8(%rsp)
movq TLSDESC_ARG(%rax), %rdi
movq (%rsi), %rax
cmpq %rax, TLSDESC_GEN_COUNT(%rdi)
ja 2f
movq TLSDESC_MODID(%rdi), %rax
salq $4, %rax
movq (%rax,%rsi), %rax
cmpq $-1, %rax
je 2f
addq TLSDESC_MODOFF(%rdi), %rax
1:
movq -16(%rsp), %rsi
sub %fs:0, %RAX_LP
movq -8(%rsp), %rdi
ret
2:
#if DL_RUNTIME_RESOLVE_REALIGN_STACK
movq %rbx, -24(%rsp)
mov %RSP_LP, %RBX_LP
cfi_def_cfa_register(%rbx)
and $-STATE_SAVE_ALIGNMENT, %RSP_LP
#endif
#ifdef REGISTER_SAVE_AREA
# if DL_RUNTIME_RESOLVE_REALIGN_STACK
/* STATE_SAVE_OFFSET has space for 8 integer registers. But we
need space for RCX, RDX, RSI, RDI, R8, R9, R10 and R11, plus
RBX above. */
sub $(REGISTER_SAVE_AREA + STATE_SAVE_ALIGNMENT), %RSP_LP
# else
sub $REGISTER_SAVE_AREA, %RSP_LP
cfi_adjust_cfa_offset(REGISTER_SAVE_AREA)
# endif
#else
/* Allocate stack space of the required size to save the state. */
sub _rtld_local_ro+RTLD_GLOBAL_RO_DL_X86_CPU_FEATURES_OFFSET+XSAVE_STATE_FULL_SIZE_OFFSET(%rip), %RSP_LP
#endif
/* Besides rdi and rsi, saved above, save rcx, rdx, r8, r9,
r10 and r11. */
movq %rcx, REGISTER_SAVE_RCX(%rsp)
movq %rdx, REGISTER_SAVE_RDX(%rsp)
movq %r8, REGISTER_SAVE_R8(%rsp)
movq %r9, REGISTER_SAVE_R9(%rsp)
movq %r10, REGISTER_SAVE_R10(%rsp)
movq %r11, REGISTER_SAVE_R11(%rsp)
#ifdef USE_FXSAVE
fxsave STATE_SAVE_OFFSET(%rsp)
#else
movl $TLSDESC_CALL_STATE_SAVE_MASK, %eax
xorl %edx, %edx
/* Clear the XSAVE Header. */
# ifdef USE_XSAVE
movq %rdx, (STATE_SAVE_OFFSET + 512)(%rsp)
movq %rdx, (STATE_SAVE_OFFSET + 512 + 8)(%rsp)
# endif
movq %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 2)(%rsp)
movq %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 3)(%rsp)
movq %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 4)(%rsp)
movq %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 5)(%rsp)
movq %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 6)(%rsp)
movq %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 7)(%rsp)
# ifdef USE_XSAVE
xsave STATE_SAVE_OFFSET(%rsp)
# else
xsavec STATE_SAVE_OFFSET(%rsp)
# endif
#endif
/* %rdi already points to the tlsinfo data structure. */
call HIDDEN_JUMPTARGET (__tls_get_addr)
# Get register content back.
#ifdef USE_FXSAVE
fxrstor STATE_SAVE_OFFSET(%rsp)
#else
/* Save and retore __tls_get_addr return value stored in RAX. */
mov %RAX_LP, %RCX_LP
movl $TLSDESC_CALL_STATE_SAVE_MASK, %eax
xorl %edx, %edx
xrstor STATE_SAVE_OFFSET(%rsp)
mov %RCX_LP, %RAX_LP
#endif
movq REGISTER_SAVE_R11(%rsp), %r11
movq REGISTER_SAVE_R10(%rsp), %r10
movq REGISTER_SAVE_R9(%rsp), %r9
movq REGISTER_SAVE_R8(%rsp), %r8
movq REGISTER_SAVE_RDX(%rsp), %rdx
movq REGISTER_SAVE_RCX(%rsp), %rcx
#if DL_RUNTIME_RESOLVE_REALIGN_STACK
mov %RBX_LP, %RSP_LP
cfi_def_cfa_register(%rsp)
movq -24(%rsp), %rbx
cfi_restore(%rbx)
#else
add $REGISTER_SAVE_AREA, %RSP_LP
cfi_adjust_cfa_offset(-REGISTER_SAVE_AREA)
#endif
jmp 1b
cfi_endproc
.size _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
#undef STATE_SAVE_ALIGNMENT
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